Can't get into BIOS/hard drive not installed error

 

I've been using a Dell XPS 13 9365. I  upgraded the machine from Windows 10 to 11 a while back and have been using it just fine for the past couple of months.

 

Recently, I was using the machine and then finished for the day, but rather than shutting it down, I closed the screen for it to go to 'sleep', with the intention of carrying on what I'd been doing the following morning. That's when everything went wrong.

 

The following day, I could not get back into the system. The screen was black and the keyboard wouldn't respond so in the end, I had no choice but to hard reboot.

 

When I did that, I only got as far as the Dell splash screen but then the system would hang with no further response possible; the longest I left it for was an hour but it got extremely hot in that time so I powered down again.

 

I did some research and read about possible hard drive issues. I powered up again and tried to get into the BIOS but the system would launch the Dell splash screen and a progress bar that got to around 25% progress and then would just hang. Tried this repeatedly with the same result each time.

 

Then tried to run the Pre-Boot Diagnostics but again, the system would hang, repeatedly, and I couldn't get into the diagnostics.

 

Wondering if it was indeed the hard drive, I bought a replacement and swapped out the existing drive for the new one. When I booted up, I could get into the BIOS and it confirmed the presence of the new drive (manufacturer and model) but on reboot, the Pre-Boot Diagnostics would load and repeatedly gave me a Hard Drive - Not Installed error message.

 

I tried running the Dell OS Support Assistant (several times) and a factory image for install was downloaded but I then got a BSoD with a System Thread Exception Not Handled error message each time I tried.

 

Having checked BIOS settings were correct  (time, date,  etc) and played around with some setting combinations (enabled/disabled legacy boot; enabled/disabled UEFI; enable/disabled secure boot) I reinstalled the old hard drive but it went straight back in to the no access to BIOS/diagnostics situation that happened first off.

 

I'm now at a loss to work out what to do next to get back into the machine, if it's even possible, and wondered if you have any suggestions, please?

 

Be grateful for any help/advice you can give. Thanks